Objective To analyze seasonal pollution characteristics of metal elements in PM2.5 in a city, and evaluate their health risks.
Methods Atmospheric PM2.5 samples were collected in autumn (from September to October 2016) and winter (from December 2016 to January 2017) in the city. Inductively coupled plasma mass spectrometry were used to detect 12 metal elements in the samples including Sb, Al, As, Be, Cd, Cr, Hg, Pb, Mn, Ni, Se, and Tl. Enrichment factor method and health risk index method were applied to analyze the carcinogenic and non-carcinogenic risks of 7 elements including Cd, Pb, As, Ni, Mn, Hg, and Cr.
Results The order of concentrations of the 12 metal elements in atmospheric PM2.5 in the city from high to low were Al > Mn > Pb > Cr > As > Se > Ni > Hg > Sb=Cd > Tl > Be in autumn, and Al > Pb > Mn > Tl > Cr > As > Se > Sb > Hg > Cd > Ni > Be in winter. The metal element concentrations in winter were all higher than those in autumn except Ni and Be. The enrichment factor of Hg was more than 2 in both autumn and winter, indicating moderate enrichment and level 2 of air pollution; the enrichment factors of Cd, Pb, As, Ni, Mn, and Cr were all less than 1, indicating no enrichment. The average annual excess risks through inhalation of four carcinogenic metal elements including Cr, Ni, Cd, and As for general populations were between 2.73×10-9 and 2.02×10-6. The average annual excess risks of three non-carcinogenic metal elements including Pb, Hg, and Mn for general populations were between 1.20×10-10 and 1.41×10-9. The average annual excess risks of seven metal elements were 1.33×10-10-2.02×10-6 for adult males, 1.20×10-10-1.82×10-6 for adult females, and 1.20×10-10-1.09×10-6 for children.
Conclusion Except Ni and Be, the average concentrations of the other selected metal elements in atmospheric PM2.5 in winter are all higher than those in winter in the selected city.
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